The present invention relates to an electric machine,                wherein the electric machine has a base body and a rotor shaft,        wherein the base body comprises at least one stator,        wherein cooling ducts for a liquid cooling medium are arranged in the base body,        wherein the rotor shaft is mounted in the base body in such a way that the rotor shaft can rotate about a rotational axis.        
Such electric machines are generally known. Purely by way of example, reference is made to DE 91 12 631 U1.
With liquid cooling media, in particular water, a substantially more efficient cooling of electric machines is possible than with gaseous cooling media, in particular air. In many cases, therefore, electric machines are equipped with water cooling.
In the prior art, for the realization of such cooling, connections are provided for the supply and discharge of the liquid cooling medium. The circulation of the liquid cooling medium is however not guaranteed by the electric machine as such. The cooling medium itself must as such also be provided from the outside. Moreover, in the prior art, at least as a rule, only the base body is water-cooled. Cooling of the rotor is, as a rule, only realized with air.